Shigella

Aka: Shigella, Bacillary Dysentery, Shigellosis, Shigella sonnei, Shigella flexneri, Shigella dysenteriae, Shigella boydii

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II. Epidemiology

  1. Most common cause of bloody Diarrhea in the United States (since 2010 when surpassed E. coli 0157:H7)

III. Pathophysiology

  1. Characteristics
    1. Facultative Anaerobic Gram Negative Rod in Enterobacteriaceae family
      1. Grouped with SS Gram Negative Bacteria (Salmonella, Shigella)
    2. Humans are the only hosts for Shigella
      1. Shigella is not a normal colonizer of the human intestinal tract (always pathogenic)
    3. Distinguished from other Enterobacteriaceae
      1. Non-motile as it has no flagella (unlike E. coli, Enterobacter, Serratia, Salmonella, Citrobacter and Proteus)
      2. Does not ferment lactose (unlike E. coli)
      3. Does not produce Hydrogen Sulfide or H2S (unlike Salmonella)
  2. Mechanism of Toxicity
    1. Only small inoculum required for infection
    2. Invades Small Bowel mucosa
    3. Produces Enterotoxin (Shiga Toxin) in colon
      1. Similar to the Enterotoxin in Enteroinvasive E. coli and Enterohemorrhagic E. coli
      2. Two different Enterotoxins have been identified (ShET-1, ShET-2)
      3. A Subunit (Active)
        1. Deactivates 60S ribosome (at 28S rRNA)
        2. Inhibits Protein synthesis, thereby killing intestinal epithelial cells
      4. B Subunit (Binding)
        1. Five B subunits are attached to each A subunit
        2. B Subunits bind colon's microvillus membrane (at Glycolipid Gb3 receptor)
    4. Toxin results in exaggerated inflammatory response, resulting in colitis and dysentary
      1. Epithelial cells are sloughed off, leaving shallow ulcerations
      2. Fluid losses are related to intestinal cell injury, unable to reabsorb fluid and Electrolytes
  3. Transmission
    1. Occurs via items contaminated with human feces (Hand contact, Fly infestation)
    2. Foodborne Sources (fecal-oral route)
      1. Contaminated drinking water
      2. Contaminated raw produce
      3. Foods contaminated by infected food handler
    3. Sexually Transmitted Infection (anal sex)
      1. More common among Men who have Sex with Men
  4. Four serotypes
    1. Shigella sonnei
      1. Most common Shigella species causing Infectious Diarrhea in industrialized countries
    2. Shigella flexneri
      1. Most common Shigella species causing Infectious Diarrhea in tropical and subtropical regions
      2. Growing Incidence as a Sexually Transmitted Infection in the United States
        1. Associated with anal sex and oro-anal sex, and presents with severe Diarrhea
        2. Multi-drug resistant and treatment requires susceptibility testing
        3. Associated with HIV Infection
    3. Shigella dysenteriae
      1. Less common outside of South Asia and Sub-Saharian Africa
    4. Shigella boydii
      1. Less common outside of South Asia and Sub-Saharian Africa

IV. Risk Factors

  1. Foodborne Sources (fecal-oral route)
    1. Preschool children
    2. Nursing Home residents
  2. Sexually Transmitted Infection (anal sex)
    1. Men who have Sex with Men

V. Symptoms

  1. Onset: 4 to 7 days (as early as 1-3 days in some cases)
  2. Duration: 24 to 48 hours
  3. Diarrhea (often severe)
  4. Tenesmus
  5. Abdominal cramps
  6. Nausea and Vomiting
  7. Lassitude
  8. Bloody stool (51% of cases)
  9. Stool mucus may be seen

VI. Signs

  1. Fever (58% of cases)
  2. Dehydration
  3. Lower abdominal tenderness

VII. Diagnosis: Flexible Sigmoidoscopy or Colonoscopy

  1. Hyperemic bowel wall
  2. Mural edema
  3. Purulent exudate

VIII. Labs

  1. Stool microscopy
    1. Stool Mucus
    2. Fecal Leukocytes present
  2. Complete Blood Count
    1. Leukocytosis or Leukopenia
  3. Routine Stool Culture
    1. Negative only after 48 hours of Antibiotics

IX. Management

  1. See Acute Diarrhea
  2. Treat Immunocompromised patients for 7-10 days
  3. Trimethoprim-Sulfamethoxazole (Bactrim) is no longer recommended due to Antibiotic Resistance
  4. Adults with Dysentery: first-line agents
    1. Ciprofloxacin 500 mg orally twice daily for 3 days or
    2. Levofloxacin 500-750 mg orally daily for 3 days
  5. Adults with Dysentery: alternative agents
    1. Azithromycin 500 mg daily for 3 days or
    2. Ceftriaxone 1-2 g IV daily for 3 days (in severe disease)
  6. Children with Dysentery: first-line agents
    1. Azithromycin 10 mg/kg/day daily for 3 days or
    2. Ceftriaxone 50-75 mg/kg/day for 2- 5 days (in severe disease)
  7. References
    1. (2015) Sanford Guide to Antimicrobial Therapy, IOS app accessed 5/8/2016

X. Complications

  1. Reactive Arthritis
  2. Hemolytic Uremic Syndrome

XI. Resources

  1. CDC Shigella
    1. http://www.cdc.gov/shigella/

XII. References

  1. Switaj (2015) Am Fam Physician 92(5): 358-65 [PubMed]
  2. Killackey (2016) Front Cell Infect Microbiol 6:38 +PMID: 27066460 [PubMed]
  3. Zaidi MB (2014) Curr Trop Med Rep 1(2):81-7 +PMID: 25110633 [PubMed]

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Related Studies

Ontology: Shigella (C0036953)

Definition (NCI) A genus of Gram-negative, non-spore forming rod-shaped bacteria in the phylum Proteobacteria.
Definition (NCI_CDISC) Any bacteria that is not assigned to the species level but can be assigned to the Shigella genus level.
Definition (MSH) A genus of gram-negative, facultatively anaerobic, rod-shaped bacteria that ferments sugar without gas production. Its organisms are intestinal pathogens of man and other primates and cause bacillary dysentery (DYSENTERY, BACILLARY).
Definition (CSP) genus of gram negative, facultatively anaerobic, rod shaped bacteria that ferments sugar without gas production; its organisms are intestinal pathogens of man and other primates and cause bacillary dysentery.
Concepts Bacterium (T007)
MSH D012760
SnomedCT 77352002
English Shigella, Shigella (organism), Genus Shigella, Genus Shigella (organism), Shigella Castellani and Chalmers 1919, shigella, shigellas, SHIGELLA, Shigella, NOS
French Shigelles, Shigella
Japanese 赤痢菌, ｾｷﾘｷﾝ
Swedish Shigella
Czech Shigella
Spanish Shigella (organismo), género Shigella (organismo), género Shigella, Shigella
Finnish Shigella
Russian SHIGELLA, ШИГЕЛЛА
Croatian SHIGELLA
Polish Pałeczki czerwonki, Shigella
Hungarian Shigella
Norwegian Shigella
German Shigella
Italian Shigella
Dutch Shigella
Portuguese Shigella
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Dysentery, Bacillary (C1527298)

Definition (MSHCZE) Infekční onemocnění střeva vyvolané Shigellami. Inkubace je 1–3–(7) dnů. Projevuje se horečkou a zejm. průjmy provázenými bolestivým nucením na stolici (tenesmy). Ve stolici může být přítomna krev. Vysoce nakažlivé onemocnění, jehož zdrojem je jen člověk (nemocný nebo bacilonosič). V klinickém průběhu u dětí či oslabených osob může být výraznější horečka a celkové příznaky. Ke komplikacím mohou patřit záněty kloubů, nervů, myokardu, hemolyticko-uremický syndrom u dětí. Střevní perforace je vzácná. Důležitá je dostatečná hydratace. Vyvíjí se vakcína. Dnes u nás probíhá spíše lehce, ale u oslabených osob (s podvýživou) může mít těžký průběh. (cit. Velký lékařský slovník online, 2013 http://lekarske.slovniky.cz/ )
Definition (MSH) DYSENTERY caused by gram-negative rod-shaped enteric bacteria (ENTEROBACTERIACEAE), most often by the genus SHIGELLA. Shigella dysentery, Shigellosis, is classified into subgroups according to syndrome severity and the infectious species. Group A: SHIGELLA DYSENTERIAE (severest); Group B: SHIGELLA FLEXNERI; Group C: SHIGELLA BOYDII; and Group D: SHIGELLA SONNEI (mildest).
Definition (CSP) dysentary caused by gram negative rod shaped enteric bacteria, most often by the genus Shigella; Shigella dysentery, Shigellosis, is classified into subgroups according to syndrome severity and the infectious species.
Concepts Disease or Syndrome (T047)
MSH D004405
ICD10 A03.9
SnomedCT 154272001, 186103005, 266175007, 274081004, 36188001
English Bacillary Dysentery, Dysentery, Bacillary, Bacillary dysentery NOS, Dysentery, Bacillary [Disease/Finding], Dysentery;bacillary, dysentery bacillary, Bacillary dysentry, bacillary dysentery, bacillary dysentery (diagnosis), Bacillary dysentery, Bacillary dysentery (disorder), bacillary; dysentery, dysentery; bacillary
Dutch bacillaire dysenterie, bacillair; dysenterie, dysenterie; bacillair, Bacillaire dysenterie, Dysenterie, bacillaire, Shigellose
German Bakterienruhr, Dysenterie, bakterielle
Portuguese Disenteria bacilar, Shiguelose, Disenteria Bacilar
Spanish Disentería bacilar, disentería bacilar, disentería basilar, disentería basilar (trastorno), disentería bacilar (trastorno), Disentería Bacilar
Swedish Rödsot
Japanese ｻｲｷﾝｾｲｾｷﾘ, 細菌赤痢, 赤痢菌感染症, 赤痢-細菌, 赤痢-細菌性, 細菌性赤痢
Czech Shigella - infekce, Bacilární dysenterie, úplavice bacilární, bacilární dyzentérie, dyzentérie bacilární
Finnish Shigelloosi
Russian SHIGELLA-INFEKTSII, DIZENTERIIA BATSILLIARNAIA, SHIGELLA-ИНФЕКЦИИ, ДИЗЕНТЕРИЯ БАЦИЛЛЯРНАЯ
Croatian DIZENTERIJA, BACILARNA
Polish Czerwonka bakteryjna, Szigelloza, Zakażenie Shigella
Hungarian bacillaris dysenteria
Norwegian Basillær dysenteri, Dysenteri, basillær
French Dysenterie bacillaire, Gastro-entérites à shigelles, Gastroentérites à shigelles
Italian Dissenteria bacillare
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Shigellosis Pathway (C2984571)

Definition (NCI_KEGG) Shigellosis, or bacillary dysentery, is an intestinal infection caused by Shigella, a genus of enterobacteria. Shigella are potential food-borne pathogens that are capable of colonizing the intestinal epithelium by exploiting epithelial-cell functions and circumventing the host innate immune response. During basolateral entry into the host-cell cytoplasm, Shigella deliver a subset of effectors into the host cells through the type III secretion system. The effectors induce membrane ruffling through the stimulation of the Rac1-WAVE-Arp2/3 pathway, enabling bacterial entry into the epithelial cells. During multiplication within the cells, Shigella secrete another subset of effectors. VirG induces actin polymerization at one pole of the bacteria, allowing the bacteria to spread intracellularly and to infect adjacent cells. OspF, OspG and IpaH(9.8) downregulate the production of proinflammatory cytokines such as IL-8, helping bacteria circumvent the innate immune response.
Concepts Functional Concept (T169)
English Shigella Infection Pathway, Shigellosis Pathway, Shigellosis
Derived from the NIH UMLS (Unified Medical Language System)

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